1. #1
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    Default Kussmaul air compressor

    Does anybody have any experience/feedback about the Kussmaul air compressor/battery conditioner unit. We have one on one of our trucks now and as far as I'm concerned you can keep it. The compressor is unable to maintain air pressure and therefore runs all of the time to the point that it's so hot you can't touch it. Now don't get me wrong, the truck doesn't leak air that much and the compressor isn't running all of the time, but when the truck is low on air the compressor seems ineffective. We have to unplug the truck and start it to bring the air pressure back up. One air pressure is full, you can plug back in and the compressor won't run. I thought the whole idea of this unit was to eliminate the procedure I just described?

    The only good thing is that when this particular truck was built, we had a cut-off switch installed on the compressor in case we ever cut and air line, the batteries could still be maintained, I never thought that we would use this switch so much.

    Do the set point for the air compressor need constant adjusting???

    We just signed contracts on two new trucks, and the manufacturer has included these units on the trucks. I want to take them off, but wanted to get some information first.

    Is it the unit or is it the install??

    Any feedback or experiences would be greatly appreciated.

    Have a great day.
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    Jay you may want to try posting your question on the NAEVT bulletin board.

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    Jay, we have the Kussmaul units on 2 Seagraves and have never had a problem with them. Sounds like it may be with the pump you have. Kussmaul has excellent customer service tech people. Try giving them a call. Good luck.

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    TCFD12, What are your cut in and cut out pressures at now? The Pump will not do over 100 psi. The most common settings are 80 psi cut in and 95 psi cut out.

    I have seen many of these and not much problem with them. If the compressor is running all the time there is an air leak.

    Also what type of oil filter system do you have? Spinner 2 systems use compressed air to spin the centrifuge. If it is no hooked up correctly the compressor will constantly try to spin the filter. If this is the case a pressure protection valve needs to be installed in the curcuit at around 92 psi and the compressor cut out set around 87 psi.

    But my first though would be that you have a air leak bigger than you think.

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    CAP22,
    I'm unsure of the cut-in and cut-out pressures. I thought that they were much lower than what you have said.

    Also the air system is not hooked into the oil filter system.

    I'm 99.99% sure that there is not an air leak. Don't get me wrong, the compressor does not run constantly 24/7, however when it does, it cannot build enough pressure to get to the shut off point. Most times when this happens is when the air system is drained while the truck is not running. (For some reason my guys find a way to drain the air, Brake checks, air horns, etc.)
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    We have these units on three trucks. The latest acted just as you describe. Our first fix was a new pressure switch. This did not fix the problem. We then replaced the pump, ( pump was shot due to constant running and overheating). When we replaced the pressure switch we installed the upgraded switch with the unload feature so the compressor does not need to start under load. So far all seems ok. The other two units have been fine.

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    SBLG makes some good points on the unloader this can really stress the small compressor.

    These units are not designed to recharge a depleted system. They are set up to maintain the system. The concern I have is the ablity for the guys to drain the system. I'm not sure how old your units are but they should have a pressure protection valve off the secondary tank for all the aux air systems. This includes pump shift, air horns, Aux tool lines and tool tanks or any other air system that is not part of the brakeing system.

    These are set normally any where from 70 psi to 90 psi, This valve will close below these pressures in order to preserve and isolate air pressure for the braking system. My sir braked units use a 90 psi valve. And the engine compressors have been dialed up to 130 psi cut out. This will produce an engine compressor cut in at around 100 psi. Most are factory set up at 110 / 115 psi cut out,with a 85/90 psi cut in.

    I have seen to many older units dynamite the spring brakes due to over use of the air horns while responding, or reduce braking capatity due to reduced system pressure. This PPV resolves that issue. But the operators need to be aware of this system. If they arrive on scene with less than 90 lbs due to a lot of brakeing the pump will not engauge. They need to be aware of this and possible wait the couple seconds it takes to come above. This hasn't been an issue though in 3 yrs.

    Sorry this is off topic but thought it should be addressed.

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    CAP22,
    I understand that the system is only designed to maintain and not replenish. It's not even doing that now. The truck is only 2 years old, and should as you say have protection devices installed.

    Sounds like I need to have our mechanic go through the system. Probably have the same problems as SBLG.

    SBLG - Did this happen to your new Saulsbury unit??

    Thanks for the input guys.
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    To me as far as the pump not being able to maintain pressure in the air system, it almost has to be a leak. Possibly even in the pump itself, if it's as overworked as you say it is when it is run, then it's probably ruined the seal or packing. Now this is somewhat off topic, but you said your guys are basically parking the truck with no air left in the tanks. The only the way I could thing of is if they're using it all doing a lot of braking getting into the station. That's fine I suppose, but it does sound like they're not letting the engines idle down once they're back in station. If any of them are equiped with turbos then they are seriously reducing the life of them by just shutting off the engine once it's parked. They almost have to be doing it this way otherwise the trucks would have built the air back up during the idling time. Another thing that it could be, is that the engine run air pump isn't working properly, so you may want to have it checked out too. You may also have a pressure relief valve sticking open on one of the airtanks, though that would be very easily recognized as you would hear the air leaking. The last thing that I can think of is if your truck is equiped with an air dryer, you could be losing your air that way, if your air has too much moisture or the dryer is just malfunctioning. I hope this helps and good luck with your fix. God bless and stay safe
    If lights, sirens, and air horns do not attract the attention of a driver, he or she is too drunk to be assisted by a paint scheme.

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    We have 3 Kussmaul air compressors. 1 is the 12V model and 2 are the 120V model. The 120V is a little bit larger and doesn't seem to have to work as hard as the 12V one.

    The oldest one is over 3 years old and we've never had a problem with any of them.

    According to the owners manual, the factory-set cut-in is 70 psi and cut-out is 90 PSI.

    Look for leaks!

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    TCFD- yes this was on the new Saulsbury unit.

    The other thing I forgot to mention was the compressors are not ment to maintain normal truck( engine driven) compressor operating pressures. If you talk to Kussmaul they say the top pressure should be around 90 PSI enough to relaese the brakes and get the unit on the road. One of our units was set to a high pressure and was having trouble , we lowered the pressure and improved the performance.

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    Hi TCFD12,

    My department has had good success with both the Kussmaul air compressors and battery conditioners. We've had some units in service for 9 years now with minimal problems. I had one of the compressors with a similar problem as you described, constant running, and it turned out to be an air leak in the system. Because the compressor was running so much it over heated and was damaged. However, we fixed the leak (tough to find) and Kussmaul repaired the compressor.

    Kussmaul is customer service orientated. I had no problems getting help and repairs done. They make a good, reliable product.

    On my last two rigs that we purchased I specked out the 110-volt model rather than the 12-volt units we retrofitted in our older units. They seem to work a little more efficient.

    Good luck,

    Capt. Lou

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